Copying apparatus is known having multiple cut sheet supply bins, one of which is used at a time, the other bin being placed in an inoperative condition. Specifically, the top sheet of the stack in use is maintained at the proper sheet-feed level, while the other stack is lowered to the lowermost position whereat, for example, the supply of sheets can be restocked.
With this arrangement, the selective changing from one stack to the other, as when changing copy sheet size, requires a relatively long time period during which the previously unused stack must be elevated from its lowermost bottom position to its top position.
The present invention shortens this change time by interposing an intermediate position, closely spaced from the feed position, so that a previously unused stack is quickly available. In addition the vertical position of all sheet stacks is bidirectionally controlled so that stack swelling, due to humidity and the like, does not inadvertently place more than one stack at its sheet feed position, while at the same time insuring that the top sheet of the used stack neither undershoots nor overshoots the sheet feed position.
In a specific embodiment, the sheet feed position and the intermediate position of the top sheet of a stack is selectively provided by a pivoted member which physically engages the top sheet and controls a switch means. By changing the positional relationship of this member's pivot and the switch means, in accordance with a desire to use or not use the stack, the top sheet thereof is bidirectionally controlled to be at the sheet-feed position or is bidirectionally controlled to be at a lower intermediate position. When a stack is to be replenished, it is lowered to a lowermost position.
The foregoining and other features and advantages of the invention will be apparent from the following more particular description of preferred embodiments of the invention, as illustrated in the accompanying drawing.